Chiral synthesis via organoboranes. 35. Simple procedures for the efficient recycling of the terpenyl chiral auxiliaries and convenient isolation of the homoallylic alcohols in asymmetric allyl- and crotylboration of aldehydes

1992 ◽  
Vol 57 (24) ◽  
pp. 6608-6614 ◽  
Author(s):  
Herbert C. Brown ◽  
Uday S. Racherla ◽  
Y. Liao ◽  
Vijay V. Khanna
Keyword(s):  
Chiral Auxiliaries ◽  
Chiral Synthesis ◽  
Homoallylic Alcohols

scholarly journals Developing a Methodology for Catalytic Asymmetric Crotylation of Aldehydes

Synlett ◽  
2021 ◽  
Author(s):  
Andrei V. Malkov ◽  
Aleksandr E. Rubtsov
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Chiral Auxiliaries ◽  
Organometallic Reagents ◽  
Total Syntheses ◽  
Base Catalysts ◽  
Homoallylic Alcohols ◽  
Stereogenic Centers ◽  
Long Time ◽  
Lewis Base Catalysts

AbstractAsymmetric crotylation has firmly earned a place among the set of valuable synthetic tools for stereoselective construction of carbon skeletons. For a long time the field was heavily dominated by reagents bearing stoichiometric chiral auxiliaries, but now catalytic methods are gradually taking center stage, and the area continues to develop rapidly. This account focuses primarily on preformed organometallic reagents based on silicon and, to some extent, boron. It narrates our endeavors to design new and efficient chiral Lewis base catalysts for the asymmetric addition of crotyl(trichloro)silanes to aldehydes. It also covers the development of a novel protocol for kinetic resolution of racemic secondary allylboronates to give enantio- and diastereomerically enriched linear homoallylic alcohols. As a separate topic, cross-crotylation of aldehydes by using enantiopure branched homoallylic alcohols as a source of crotyl groups is discussed. Finally, the synthetic credentials of the developed methodology are illustrated by total syntheses of marine natural products, in which crotylation plays a key role in setting up stereogenic centers.1 Introduction2 Pyridine N-Oxides as Lewis Base Catalysts3 Bipyridine N,N′-Dioxides as Lewis Base Catalysts4 Chiral Allylating Reagents5 Synthetic Applications6 Concluding Remarks

Synthesis of Axially Chiral 2,2’-Bisphosphobiarenes via a Nickel-Catalyzed Asymmetric Ullmann Coupling: General Access to Privileged Chiral Ligands without Optical Resolution

2020 ◽  
Author(s):  
Ziqing Zuo ◽  
Raphael Kim ◽  
Donald Watson
Keyword(s):  
Optical Resolution ◽  
Chiral Ligands ◽  
Chiral Auxiliaries ◽  
Axially Chiral ◽  
Ullmann Coupling

<div><p>We report an asymmetric Ullmann-type homocoupling of <i>ortho-</i>(iodo)arylphosphine oxides and <i>ortho</i>-(iodo)arylphosphonates that results in highly enantioenriched axially chiral bisphosphine oxides and bisphosphonates in good yields and excellent enantioselectivities. These products are readily converted to enantioenriched biaryl bisphosphines without need for chiral auxiliaries or optical resolution. This process provides a straightforward and practical route for the development of previously uninvestigated atroposelective biaryl bisphosphine ligands.</p></div>

Synthesis of Functionalized Homoallylic Alcohols Using Potassium Allyltrifluoroborate Promoted by Microwave Irradiation

2015 ◽  
Vol 2 (4) ◽  
pp. 403-408 ◽  
Author(s):  
Gilson B. da Silva ◽  
Jucleiton J. R. de Freitas ◽  
Paulo H. Menezes ◽  
Ivani Malvestiti
Keyword(s):  
Microwave Irradiation ◽  
Homoallylic Alcohols
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